EUS-FNA and FDG-PET are complementary procedures in the diagnosis of enlarged mediastinal lymph nodes

Transoesophageal endosonography with fine needle aspiration (EUS-FNA) and 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography (FDG-PET) are now standard diagnostic procedures of the mediastinum. Our aim was to compare their value in the assessment of enlarged mediastinal lymph nodes detected by computed tomography.

Forty consecutive patients with a suspicion of cancer or a history of pulmonary, digestive, urogenital or mammary neoplasia and presenting with supracentimetric lymph nodes on computed tomography underwent whole body FDG-PET and EUS-FNA. Final diagnosis of malignancy was obtained by cytology, surgery or long-term follow-up.

EUS-FNA showed a sensitivity, specificity and accuracy for detection of malignancy of 793, 100 and 85%, respectively. The biopsy material was adequate for cytological examination in 37 patients. Sensitivity, specificity and accuracy of PET were 100, 54.5 and 87.5%, respectively. FDG-PET correctly diagnosed the primary site in 27 patients, and showed additional unknown extrathoracic metastatic sites in 15 patients. The five false positive results observed with FDG-PET consisted in a final diagnosis of sarcoidosis, tuberculosis, anthracosilicosis and reactive lymph nodes, respectively. The association of FDG-PET and EUS-FNA avoided more invasive procedures (mediastinoscopies or staging surgery) in 34 patients.

EUS-FNA and FDG-PET are complementary diagnostic procedures combining the high sensitivity of FDG-PET and the high specificity of EUS-FNA to accurately diagnose malignancy in enlarged mediastinal lymph nodes identified by CTscan. The combination of the two procedures in selected cases with pulmonary cancer or extra-thoracic tumours avoided more invasive diagnostic and surgical procedures.